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The order parameter in Fe-based superconductors remains elusive. To get insight into the pairing mechanism, it is crucial to determine the gap structure in the superconductors like FeSe or pnictides. Though with lower T c, FeSe has the simplest structure, and this very simplicity could provide the most appropriate venue of understanding both the order parameter and the superconducting mechanism of Fe-base superconductors. Motivation

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Johnston, 2010

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( Subedi et al., 2008 )

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Specific heat as the probe Revealing the superconducting order parameter from the specific heat Information from k-space integration. Non phase-sensitive. Surprisingly selective if well excuted

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Fig. 4 The specific heat of MgB 2. The dashed lines are determined by the conservation of entropy around the anomaly and used to estimate ΔC/T c. Inset: Entropy difference ΔS by integration of ΔC/T.